Embodiments of the inventive concept relate generally to electronic memory technologies. More particularly, embodiments of the inventive concept relate to nonvolatile memory devices and related transistor configurations.
Semiconductor memory devices are fabricated using semiconductor materials such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (InP). Semiconductor memory devices can be roughly divided into two categories according to whether they retain stored data when disconnected from power. These categories include volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power. Examples of volatile memory devices include static RAM (SRAM), dynamic RAM (DRAM), and synchronous DRAM (SDRAM), and examples of nonvolatile memory devices include read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory device, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), and a ferroelectric RAM (FRAM).
In an effort to improve the integration density of nonvolatile memory devices, researchers have recently developed nonvolatile memory devices in which memory cells are arranged in a three-dimensional array. One challenge in developing these devices is to ensure their structural integrity. For example, where features are stacked on top of each other in a three-dimensional array, some of the features may be formed on air gaps or spaces, which can weaken their structure.